I. Field of the Invention
The present invention relates generally to a method and apparatus for repairing a ruptured tire. More particularly, the present invention relates to a method for repairing a rupture in a radial tire's sidewall by using a removable reinforcement pad having a composite construction including a layer of metal material.
II. Description of the Prior Art
Previously known sidewall repairs on steel radial truck tires, automobile tires, earth moving or farm vehicle tires have been tested to be extremely safe. Unfortunately, they appear unsafe when viewed by weigh station inspectors or state police inspectors as the repair method creates a bulge in the sidewall of the tire. This bulge creates the illusion that a separation in the sidewall exists. Although this problem is merely one of appearance and not safety, it may be hard to convince the public of this. As a result, uninformed personnel at weigh stations or highway patrol may require truckers to remove repaired radial tires as they look unsafe for road travel.
The method for repairing a rupture in a radial sidewall requires a repairman to properly skive out the injury and fill the hole resulting from the rupture with uncured rubber. A section repair patch, formed usually of a composite structure of cured and uncured rubber, is laid behind the hole. A tube and flap are then placed in the tire and the tire is mounted on a rim. An envelope is placed over the tire and the whole assembly is placed in a curing chamber.
The tire is pressurized to 115 psi and the curing chamber is heated to 250.degree. F. When the chamber reaches 250.degree. F., the uncured rubber in the ruptured hole begins to flow and the section repair patch behind the hole becomes pliable. With the difference in pressure between the tire and the chamber, the tire tube tends to push the section patch through the hole in the ruptured area. This creates a bulge in the repair area during the curing process. This bulge becomes a permanent part of the sidewall repair as it is permanently cured in this position.
Attempts have been made to create a stronger section repair patch to overcome the pressure differential. Section repair patches have previously been made with fibrous cords of material, such as nylon cording, to prevent bulging. Other methods of patching sidewall ruptures include clamping the repair area between a C-clamp to prevent the pressure differential from forcing the section repair through the ruptured area.
Another method developed to prevent bulging is described in U.S. Pat. No. 4,375,231 to Bubik et al. This method requires forcing the section repair patch into the ruptured area prior to the curing process. This requires an extra step in the repair process and the application of different pressures to force the section repair patch through the ruptured area depending on the tire to be repaired.
A disadvantage of these previous methods is that a bulge may still occur in the sidewall of the tire during the curing process. Previous repair methods use section repair patches formed of multiple layers of nylon, polyester or rayon. Although such section repair patches successfully reinforce the tire injury area, the existing pressure differential tends to push the patch through the hole, causing bulging. Further, steady pressure on the repaired area during use of the tire causes the patch to stretch and separate.
A still further disadvantage of these previous methods of repair is the multiplicity of steps required to prevent the bulge in the sidewall of the tire. The repair no longer becomes a simple procedure, but requires the precise measurement of pressure within the curing chamber. Other methods require the use of additional tools, such as a C-clamp, to prevent bulging.
A still further disadvantage is that the section repairs described above become a permanent part of the tire and are, therefore, not removable after the curing operation. This creates additional costs as none of the material is reusable.